Use of extrusion aids for successful production of Kollidon^® CL-SF pellets by extrusion-spheronization

Fine particle ethylcellulose (FPEC) or poly(ethylene oxide) (PEO) addition to a Kollidon CL-SF was investigated to address low yield and poor sphericity in extruded-spheronized pellets.

The success of crospovidone as a diluent in extrusion-spheronization was dependent on a small particle size of the polymer. FPEC aided production of rugged and spherical pellets using a large particle size grade, Polyplasdone^® XL. PEO acted as an extrusion-spheronization aid when ethylcellulose was the diluent. These extrusion-spheronization aids could serve in this role when Kollidon^® CL-SF (K CL-SF) is the diluent.

The influence of formulation and process variables on pellet properties was investigated using design of experiments. A planetary mixer was used to prepare powder blends and the wetted mass after addition of water. An EXD 60 extruder produced extrudate that was spheronized in a Q230 marumerizer. Wet pellets were dried in a forced-air oven.

FPEC improved rounding up but reduced pellet yield. Poly(ethylene oxide) imparted desired characteristics to the wetted mass, the extrudate, and the spheronized pellets. Pellet average diameter, yield, sphericity, aspect ratio, friability, and dissolution profile were assessed. Equations for pellet characteristics facilitated discussion of the influences of factors and their interactions. Optimization was performed on pellets that included PEO.

PEO proved to be an exceptional extrusion-spheronization aid in the preparation of pellets using K CL-SF. It facilitated wetted mass extrusion with minimal mass loss to the extruder, and markedly improved the sphericity of the pellets produced by marumerization. Immediate release pellets were obtained.